1. Field of the Invention
The present invention relates to rotary handle operators for circuit breakers. More specifically, the present invention provides an improved lockout mechanism for a rotary handle operator.
2. Description of the Related Art
Most circuit breakers include an operating lever which moves linearly between an on position and an off position. The handle is connected to the movable contacts of the circuit breaker through an over-center toggle device which separates the contacts, simultaneously moving the operating lever, in response to overcurrent conditions.
For certain circuit breaker applications, it is desirable to provide an interface between the operating lever and the human operator. Such an interface will frequently take the form of a rotary handle operator, wherein a rotary handle is utilized to actuate a linearly moving member, which in turn actuates the circuit breaker""s operating handle.
When servicing the equipment protected by the circuit breaker, it is desirable to lock out electrical power to the equipment, preventing any possibility of injury to those servicing the equipment. Therefore, it is desirable to be able to lock the handle of the rotary handle operator, and therefore the operating lever of the circuit breaker, in the open position.
An example of a lockable rotary handle operator is described in U.S. Pat. No. 5,219,070, issued to K. A. Grunnert et al. on Jun. 15, 1993, and assigned to Westinghouse Electric Corp. The rotary handle operator includes a rotatable handle engaging a pinion gear, which in turn engages a slidably mounted rack. The rack engages the circuit breaker handle. Rotating the handle will therefore rotate the pinion gear, causing the rack to move, moving the circuit breaker""s operating lever from one position to the other. When the handle is in the off position, inserting the shackle of a padlock through an aperture in the handle will push a spring-biased pin into an aperture in the rotary handle operator""s housing, thereby resisting rotation of the handle from the off position.
Another presently available rotary handle operator includes a pivoting lock-off plate moving between an unlocked position wherein rotation of the rotary handle operator""s handle is permitted, and a locked position wherein one end of the lock-off plate fits within a slot in the rotary handle operator""s housing, thereby resisting movement of the handle. The lock-off plate is biased by a coil spring into the unlocked position. An aperture in the opposite end of the lock-off plates protrudes upward from the handle in the locked position, permitting insertion of the shackle of a padlock into the aperture, thereby securing the lock-off plate in the locked position.
It is desirable to reduce the number of components within a rotary handle operator""s locking mechanism, thereby reducing both the cost of these components and the number of assembly steps in building the rotary handle operator.
The present invention provides an improved locking mechanism for a rotary handle operator for a circuit breaker.
The improved locking mechanism includes a lock plate pivotally secured within the rotary handle operator""s handle. The lock plate includes a live spring, molded as one piece with the lock plate, for biasing the lock plate into its unlocked position. The lock plate includes one end dimensioned and configured to abut an abutment depending from the housing of the rotary handle operator when the handle is in the off position, and the lock plate is in the locked position, and another end defining an aperture dimensioned and configured to permit passage of a padlock""s shackle when the lock plate is in the locked position.
The rotary handle operator includes a housing on which a pivotally mounted handle is secured. The handle is secured to a gear so that rotation of the handle will simultaneously rotate the gear. Rotation of this gear will actuate movement of a sliding member, possibly through the interaction of a second gear between the first gear and the sliding member, so that the sliding member may thereby be reciprocated along a linear path. The sliding member engages the operating lever of the circuit breaker, so that movement of the sliding member will control movement of the circuit breaker""s operating handle. Rotation of the rotary handle operator""s handle from the off position to the on position will therefore cause the sliding member to move the circuit breaker""s operating lever from the off position to the on position, while rotation of the handle from the on position to the off position will likewise cause the sliding member to move the circuit breaker""s operating lever from its on position to its off position.
When the rotary handle is in the off position, the lock plate may be pivoted against the bias of the spring so that the aperture protrudes from the handle. Inserting the shackle of a lock, such as a padlock, through the aperture within the handle secures the lock plate in the locked position, thereby resisting movement of the handle to the on position. Upon removal of the lock""s shackle, the lock plate will return to the unlocked position under the bias of the spring, permitting rotation of the handle.